Steering columns transmit the rotation of the steering wheel to the wheels to modify their orientation, for example according to the following order: the steering wheel, the steering column, the intermediate axle, the rack and finally the wheels.
Current steering columns allow adjustment of the steering wheel in depth and/or in height by way of an axial adjustment of the columns. A steering column conventionally includes:                a support, also termed a bracket, intended to be fixed to the chassis of the vehicle according to a single position,        an adjustable body mounted to be mobile in the support element,        a tube mounted on the adjustable body and connected to the steering wheel, and        a device for clamping and immobilizing the adjustable body in position on the support.        
In known adjustable steering columns a control enables placing the clamping and immobilizing device in a position termed the locked position in which the adjustable body is immobilized in position on the support and a position termed the unlocked position in which the adjustment of the steering column in depth and/or in height is allowed, the adjustable body no longer being immobilized in position on the support.
On an axially adjustable steering column, the requirement is to have means for axially locking the required position of the column and a device for dissipating or absorbing the energy generated in the event of a front-end collision of the vehicle with an obstacle following the impact of the driver on the steering column.
Accordingly, in the event of a front-end collision, to reduce the impact on the driver, should he strike the steering wheel, the tube can generally move relative to the adjustable body. For example, the tube can travel a distance termed the stroke in the adjustable body to absorb the energy.
On the other hand, as the adjustable body must remain in position, notably to avoid damaging certain units of the vehicle by descending too low, a system is provided to immobilize the adjustable body, notably in its locked position.
For example, the document WO9309016A1 describes a jaw mechanism placed on the outside of the body that is moved away from or toward the body with a rotation movement. The jaw bears on the body to immobilize the latter in the event of an impact.
However, this mechanism has a certain overall size because space must be provided beside the column to allow the movements of the ratchet.